I. Field of the Invention
The present invention relates generally to medical instruments and, more particularly, to a scleral dissector.
II. Description of the Prior Art
Following extracapsular surgery, an artificial lens is frequently implanted into the eyeball in order to restore normal, or near normal, vision to the patient. The lens can be implanted either into the anterior chamber, iris or posterior chamber of the eyeball although the modern trend is toward posterior chamber lens implants.
In order to implant the artificial lens, an incision is made through the eyeball and the artificial lens is inserted through the incision and implanted at the desired position in the eyeball. The incision is then sutured and allowed to heal.
Previously, the incision in the eyeball has been made at the junction between the cornea and the sclera which provided direct access to both the anterior and posterior chambers as well as the iris. One disadvantage of this procedure, however, is that after the incision has been sutured, the patient suffers from very severe stigmatism resulting from distortion of the cornea at the point of the incision. Such stigmatism oftentimes lasts for a period of months and then vanishes but, in other cases, the stigmatism is permanent.
With reference to prior art FIG. 1, in order to avoid stigmatism following the lens implanation, many surgeons now make a radially extending incision 10 through the sclera 12 at a position radially spaced from the cornea 14 so that the incision extends only partway through the sclera 12. A prior art scleral dissector 16 having an elongated handle 18 with a cutting blade 20 extending laterally outwardly from one end is then inserted into the incision 10 and used to make a tangentially extending incision through the sclera 12 and towards the cornea 14. In doing so, the scleral dissector 16 forms a flap 24 in the sclera 12. This flap 24 is then lifted to complete an incision through the sclera 12 and through which the artificial lens is inserted and implanted in place.
While the above described procedure effectively eliminates the problem of severe stigmatism following the lens implantation, great care must be exercised by the surgeon in cutting the flap 24 since the sclera 12 is very thin walled. Thus, if the dissector 16 is tilted as shown in exaggeration by the dashed and dotted line at 16' in FIG. 1, the blade 20 will cut through the outer surface of the sclera 12 and destroy the flap 24. Conversely, if the dissector is tilted as shown in exaggeration by the dashed line at 16", the blade 20 can cut through the inner surface of the sclera 12 at a position radially spaced from the cornea 14. In either event, extensive repair of the eyeball is required.